Precious metals are used as protective films on surfaces for a variety of reasons. In the jewelry trade, it is used to improve the appearance of an article as in platinum plated jewelry. In other applications, it is used to protect against corrosion of metals and other surface materials. In the electrical arts protective films made of precious metals are used as conduction paths in electrical circuits and as contact surfaces in devices with electrical contacts. Gold is used extensively in these applications with great success. However, other metals are useful in such applications, including platinum because of its different color and possible superior properties for some applications.
Platinum and platinum alloys are used extensively in a variety of industrial applications. Typical examples are the jewelry trade where such films are used to protect surfaces against corrosion and to improve appearance. Platinum films are also used to protect silverware, certain scientific instruments and standard weights. Platinum is also used in the electrical arts in various electrical devices and electronic circuits and in the chemical field for electrodes and catalysts.
Because of chemical inertness and reasonable hardness, platinum is often used as an electrical contact material in electrical connectors, relay contacts, switches, etc. Various platinum alloys such as platinum-rhodium, platinum-silver, platinum-gold and platinum-nickel are also useful for the same applications or other applications.
Highly desirable is a process for plating platinum from an aqueous solution which is rapid and yields platinum and platinum-alloy films which are ductile and adherent. In many applications, it is desirable that the platinum plating bath not chemically attack the surface being plated so that the bath remains uncontaminated during the plating process.
The literature on the electroplating of platinum is not very extensive. A. Brenner has summarized electroplating of platinum metal and alloys (see Electrodeposition of Alloys, Principles and Practice, Vol. II, Academic Press, 1963, pp. 542-546). Several platinum electroplating baths are described in a book by F. A. Lowenheim entitled Electroplating, McGraw-Hill, 1978, pp. 298-300. Particular baths are also disclosed in Metal Finishing, published by Metals and Plastics Publications, Inc., Vol. 79, No. 1A (1981) pp. 305-306. An electroplating bath for platinum is also described by W. Keitel and H. E. Zschiegner in Transactions of the Electrochemical Society, Vol. 59, page 273 (1931).